Glutamine is the most abundant amino acid in the body. It is a “nitrogen shuttle” between tissues and a fuel for enterocytes, colonocytes, lymphocytes and proliferating cells. The function of the gut is impaired in patients with glutamine deficiency, particularly because of the loss of protection against the translocation of bacteria and/or endotoxin from the gut lumen into the portal circulation. Glutamine depletion occurs in critically ill and injured patients, and may contribute to the high rate of infection and muscle depletion.
Enteral administration of glutamine has conferred health beneficial effects in patients with different indications. In intensive care unit patients with multiple organ dysfunction administration of glutamine decreased infectious complications in the patients (Houdijk et al., Lancet, 352:772-776, 1998). Similar effects were observed in patients undergoing bone marrow transplantation receiving glutamine supplemented parenteral nutrition (Ziegler et al., Annals Internal Medicine, 116:821-828, 1992). Another example is patients with short bowel syndrome, which had a substantial improvement of their absorption capacity following glutamine supplementation (Byrne et al., Annals of Surgery, 222:243-255, 1995). Oral glutamine supplementation during and after chemotherapy has also been shown to significantly reduce both the duration and the severity of chemotherapy-associated stomatitis. It was concluded that oral glutamine appeared to be a simple and useful measure to increase the comfort of many patients at high risk of developing mouth sores as a consequence of intensive cancer chemotherapy (Anderson et al., Cancer 1998; 83:1433-9). Nutritional supplementation of glutamine after intensive exercise has also decreased the incidence of infections, particularly of upper respiratory tract infections (Castell, Amino acids 2001; 20(1):49-61). However, the precise effect of glutamine on immunodepression has not yet been established.
A major technical difficulty with glutamine is that during processing and storage glutamine is easily converted to glutamic acid (glutamate), i.e. glutamine is a relatively unstable compound that is difficult to incorporate into formulas intended for oral administration. Furthermore, the orally administered glutamine will in the sour environment of the stomach to a high degree be converted into glutamic acid and never reach the intestine and be absorbed as glutamine.
Arginine enhances the immune function and promotes wound healing. Administration of arginine has been used in postoperative patients and patients under intensive care. In most clinical studies arginine has been administered together with other substances such as RNA and fish oil. There are indications that administration of arginine modulates post-operative immune response. Daly, John E., et al., Surgery 112:55-67, 1992 show that enteral nutrition with supplemental arginine, RNA and omega-3-fatty acids in patients after operation improves the immune defence through different mechanisms. Arginine reduces complications in patients undergoing chemoradiation and surgery (Tepaske et al., 2001; Lancet 358: 696-701), and reduces length of stay for intensive care unit patients (Bauer et al., 1995, Critical Case Medicine 23: 436-449).
An increased survival could be observed in animals fed with an arginine-supplemented diet. Quantitative colony counts and the calculated percentage of remaining viable bacteria showed that the ability to kill translocated organisms was signify-cantly enhanced in animals receiving arginine (Adawi, D., et al., 1997, Hepatology 25: 642-647).
Strains of Bifidobacterium spp., that is bifidobacteria, are often present in high numbers in the human colon, especially in breast fed babies. Bacteria from the Bifidobacterium spp. are regarded as probiotics, that is live bacteria that upon ingestion provide health beneficial effects to the host. High numbers of Bifidobacterium spp. in colon have been claimed to have health beneficial effects. However, the course of action of said beneficial effects is largely unknown.